1. Field
The present disclosure relates generally to induction welding and, in particular, to using induction welding to attach a skin to a number of stiffeners. Still more particularly, the present disclosure relates to a method and apparatus for attaching a skin to a number of stiffeners using at least one stack-up comprised of a susceptor layer and one or more protective layers.
2. Background
Induction welding is a type of welding that uses electromagnetic radiation to heat a workpiece. Typically, an induction welding system includes one or more induction coils that are energized with a radio frequency electric current, which in turn, generates a high-frequency electromagnetic field. This electromagnetic field may heat the workpiece.
When the workpiece is electrically conductive, the heating may take the form of resistive heating that occurs due to induced currents, referred to as eddy currents. When the workpiece is a ferromagnetic workpiece, the heating may be caused by hysteresis. In particular, the electromagnetic field may cause repeated distortions of the magnetic domains of the ferromagnetic workpiece. Typically, a combination of these two effects is involved in the heating of a workpiece.
In some cases, susceptors may be used to inductively weld materials together. As used herein, a “susceptor” is an object comprised of a compound that is capable of absorbing the electromagnetic energy generated by an induction coil. In response to absorbing this electromagnetic energy, the compound is heated and then loses this heat to materials surrounding the compound through thermal conduction. A susceptor may take the form of, for example, without limitation, a susceptor wire.
Susceptors may be used to inductively weld materials such as, for example, without limitation, nonmagnetic materials, electrically insulated materials, magnetic materials, electrically conductive materials, composite materials, metallic materials, nonmetallic materials, other types of materials, or some combination thereof. Susceptors may be used to inductively weld materials together without requiring that a current path travel through the materials being welded together.
However, in some situations, when using susceptor wires and large induction coils in the form of solenoids to perform induction welding, undesirable current paths may be formed. These current paths may cause portions of a workpiece that were not intended to be heated to become hot. In some cases, these current paths may cause portions of a workpiece to become overheated. This overheating may cause undesired inconsistencies to develop in and/or on the workpiece. For example, a portion of a workpiece that is overheated may burn. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.